Verified answer

You don't need a passport to go to Los Algodones or anywhere in the border, but you do need a passport to go further south in Mexico, I think it is like 40 kilometers... but you DO need a passport to go back to the US, regardless of your citizenship... you might try to go back using an ID but it is going to be a hassle..

The law requires a passport. However Mexico will let you in without a passport. You may get hassled and delayed trying to get back into the U.S. People do it , but I think it is very risky.

you don't need a passport to go from here to Mexico(anywhere in Mexico ) You need the passport to comeback to USA

I'm almost certain you do now...I traveled in 2007 and only had to have a birth certificate, but I think they changed that in 2008.

Yes. Maybe you can go without one but for sure you will have a lot of problems trying to come back.